One Night In October
One Night In October Olivia Dunham is informed by Broyles that the Fringe division of the parallel universe has requested their help to locate John McClennan, a highly intelligent serial killer that has taken more than 20 victims, drilled into their skull, and killed them by freezing their brains from the inside. The parallel Fringe wants Olivia to bring the prime universe's version of John, a professor of forensic psychology, to examine the last known residence of the Parallel John and try to deduce where he may be. Still cautious of the parallel Fringe's intentions, Olivia agrees to help. She meets with the Prime John, explaining their need, but without revealing the existence of the parallel universe. He offers to help, and willingly takes a tranquilizer that puts him to sleep during the transport to the parallel universe through the Machine Room bridge. As Olivia waits with the parallel Lincoln Lee, Fauxlivia dresses as Olivia, and watches over John as he investigates the house. John becomes suspicious that many aspects of the home's owner match his own, but is able to identify that the owner was jealous of those people that were happy. John reveals that he himself is hiding a secret, a need to understand why people are happy that as a kid drove him to homicidal tendencies, killing small creatures; he mentions a change in his life that took him into criminal psychology but does not elaborate. When John finds a picture of his father, a farmer, he realizes something is amiss and storms out. Olivia is forced to try to stop him, and John soon becomes aware that he is in the parallel universe. Soon, another victim is taken. Olivia and the parallel Fringe team allows John time to recover in the bathroom before tracking this new case, but soon discover he has escaped. They come to agree that John probably has left towards the remains of his father's farm and head out. John, meanwhile, has met with his parallel self, who is preparing the latest victim in a makeshift machine that allows him to directly connect to the victim's brain and experience their happy memories but that ultimately kills the victim. The two Johns briefly struggle with the idea of their doppelgangers, but soon learn that while they shared the same youth, their paths diverged when their respective fathers discovered their cache of dead animals. In the parallel universe, John's father caught him and punished him, while in the prime universe, John ran away, stumbling and falling over. He was later rescued by a woman named Marjorie, who, even on seeing the dead animals, loved and embraced him, telling him "Even when it’s the darkest, you can step into the light", a phrase he has since used to subdue his homicidal nonattendance. The Parallel John becomes jealous of this, knocks his doppelganger out and hooks him to the machinery, demanding he tell him more about Marjorie. Olivia and the Fringe team converge on the farmhouse but find it empty. Nearby they find the remnants of a barn, and soon find a storm shelter nearby. Entering it, they find both the victim, still alive, and the prime version of John, recovering from the trauma, while a shaken parallel version of John cowers nearby, overwhelmed with the impact that Marjorie had on John's life and regretting the lives he has taken. He commits suicide just as the Fringe team finds him. John is returned to the parallel universe and taken to a hospital, the incident having made him forget the memories of the parallel universe as well as Marjorie, but he still remembers what she said to him. Throughout the episode, Walter has covered up every reflective surface in his lab, trying to avoid the vision of Peter that he sees. In the finale, Walter starts hearing Peter's voice, telling him that he needs his help, leaving Walter even more panicked as to its source.